This invention relates to improvements in torsional vibration dampers, especially to those employing so-called split flywheels, wherein a first or primary rotary flywheel or mass is connectable to the output shaft of a prime mover (for example, the rotary output shaft of an internal combustion engine in the power train of a motor vehicle), a second or secondary rotary flywheel or mass which can be connected to at least one rotary input element of a change-speed transmission in the power train of the vehicle, first energy storing means which serves to yieldably oppose rotation of the flywheels relative to each other, and second energy storing means operating in parallel with the first energy storing means and also serving to oppose rotation of one flywheel relative to the other flywheel.
Numerous torsional vibration dampers of the above outlined character are utilized in the power trains of motor vehicles to reduce the likelihood of transmission of undesirable forces and/or movements between the flywheel which receives torque from the prime mover and the flywheel which is connected to one or more rotary elements of a second rotary component (e.g., one or more rotary input shafts in the transmission) of the power train. Depending upon the nature of operation of the motor vehicle, the angular displacement of one flywheel relative to the other flywheel can vary within a rather wide range. Furthermore, the nature of operation of the prime mover can be such that, under certain normally undesirable circumstances, the prime mover causes the primary flywheel to oscillate. Such oscillatory movements of the primary flywheel should not be transmitted to the secondary flywheel because they would be likely to entail damage to the transmission of the power train and/or to generate undesirable noise.
Examples of presently known power trains which employ torsional vibration dampers with primary and secondary flywheels and several energy storing members which oppose rotation-of the flywheels relative to each-other are-those disclosed in commonly owned U.S. Pat. No. 4,729,465 (granted Mar. 8, 1988 to Reik for “ASSEMBLY FOR COMPENSATING FOR FLUCTUATIONS OF TORQUE WHICH IS TRANSMITTED BY AN INTERNAL COMBUSTION ENGINE”), U.S. Pat. No. 4,751,992 (granted Jun. 21, 1988 to Maucher et al. for “COMPOSITE FLYWHEEL WITH SLIP CLUTCH”), U.S. Pat. No. 4,889,009 (granted Dec. 26, 1989 to Oswald Friedmann et al. for “TORQUE TRANSMITTING MECHANISM”) as well as in numerous additional U.S. patents granted to the assignee of the present application.